Mammalian cells contain a large number of phospholipases that hydrolyse phospholipids in a structurally specific manner for production of a myriad of products, many of which have potent biological activity. There has been considerable interest in characterising these enzymes because of their role in production of lipid mediators of inflammation. Since the first studies 20 years ago showing that mammalian cells contain a cystolic calcium dependent phospholipase A2 (cPLA2) specific for arachidonic acid, an extensive amount of evidence has substantiated a primary role for cPLA2 as the key enzyme that mediates the release of arachidonic acid for the production of eicosanoids.
The enzyme cPLA2 contributes to the pathogenesis of a variety of diseases particularly those in which inflammation plays a primary role implicating a role for inflammatory lipid mediators in disease pathogenesis. The inhibition therefore of such lipase enzymes offers a potential therapy for inflammatory conditions in particular chronic inflammatory conditions such as those above, psoriasis and glomerulonephritis.
The phospholipase A2s are a group of enzymes that release unsaturated fatty acids from the sn2 position of membrane phospholipids. Once released, the fatty acids are converted by various enzymes into biologically very important signalling molecules. Release of arachidonate initiates the arachidonate cascade leading to the synthesis of eicosanoids such as prostaglandins.
Eicosanoids are important in a variety of physiological processes and play a central role in inflammation. In Inflammation, Vol. 18, No. 1 1994, Andersen et al identify the presence of certain phospholipase A2s in psoriatic human skin.
It is therefore believed that inhibition of phospholipase A2 enzymes should have potential in curing some of the inflammatory symptoms, including epidermal hyperproliferation due to increased leukotriene production, related to eicosanoid production and cell activation in both epidermis and dermis in psoriasis.
Psoriasis is a common, chronic, inflammatory skin disorder. Psoriatic tissue is characterised by chronic inflammation in both epidermis and dermis, the disease being further characterised by hyperplasia of epidermal keratinocytes, fibroblast activation, alteration of eicosanoid metabolism, and leukocyte infiltration.
Glomerulonephritis, also known as glomerular nephritis, abbreviated GN, is a renal disease characterized by inflammation of the glomeruli, or small blood vessels in the kidneys. It may present with isolated hematuria and/or proteinuria or as a nephrotic syndrome, acute renal failure, or chronic renal failure. Glomerulonephritis is categorised into several different pathological patterns, which are broadly grouped into non-proliferative or proliferative types.
The glomerulus is a unique vascular network with three specialised types of cell: the endothelial cell, the mesangial cell and the visceral epithelial cell. Mesangial cells (MC) serve a number of functions in the renal glomerular capillary including structural support of the capillary tuft, modulation of the glomerular hemodynamics and a phagocytic function allowing removal of macromolecules and immune complexes. The proliferation of MC is a prominent feature of glomerular disease including IgA nephropathy, membranoproliferative glomerulonephritis, lupus nephritis, and diabetic nephropathy.
Reduction of MC proliferation in glomerular disease models by treatment with, for example, a low protein diet has been shown to produce extracellular matrix expansion and glomerulosclerotic changes. MC proliferation inhibitors may therefore offer therapeutic opportunities for the treatment of proliferative glomerular disease.
Mesangial proliferative glomerulonephritis is a form of glomerulonephritis which involves inflammation at the kidney glomeruli. The mesangial cells which are a part of the glomerular capillaries, increase in size giving the glomeruli a lumpy appearance. The disorder usually causes nephritic syndrome which represents protein loss in the urine. It may be present as acute, chronic or rapidly progressive glomerulonephritis and may progress to chronic renal failure.
The present inventors seek new treatments for, inter alia, chronic inflammatory conditions such as glomerulonephritis and associated conditions like diabetic nephropathy and retinopathy, psoriasis, dermatitis, rheumatoid arthritis and hyperproliferative disorders such as cancer.